The Dyna Z Cone from No7 Contact Lenses is an easy-to-fit corneal RGP for Keratoconic patients. It uses similar fitting strategies to other popular Keratoconic corneal RGP designs.
Introduction
Steep central cones achieve the best visual outcomes with smaller diameter RGP lens designs. However, inferior cones may need a larger diameter. The Dyna Z Cone lens comes in a standard 8.80 mm diameter but is available from 8.00mm to 9.90mm in 0.1mm steps. The BOZR ranges from 4.50mm to 8.50mm in 0.05mm steps. Our recommended material is Optimum Extra but other materials from our range can be used on request.
Starting Trial Lens
Start with a diameter of 8.80mm and use the lens closest to the average of the central K’s, or the average of the Sim K’s.
Example:
7.00 x 180 by 6.50 x 90.
>> Select a trial lens with a BOZR of 6.75mm.
Fitting Assessment
The fluorescein pattern should look as aligned as possible, with light feather touch. Note that highly irregular corneas will not have perfect-looking patterns. The goals are a comfortable fit, adequate vision and a healthy cornea.
If there is central touch, then steepen the BOZR until slight feather touch is seen. However, excessive central clearance results in poor V/A; in this case, flatten the BOZR until slight feather touch is seen.
If the lens decenters inferiorly, then increase the diameter. For superior decentration, decrease the diameter. Increase or decrease the edge profile as needed to produce adequate edge clearance.
Troubleshooting
Central touch?
Steepen BOZR until slight feather touch is seen.
Central pooling?
Flatten the BOZR until slight feather touch is seen.
Inferior decentration?
Increase the diameter.
Edge Profile
The desired edge lift will show about 0.15mm of clearance. The Dyna Z Cone lens starts with a standard edge lift. Flatter or steeper edge lifts are available in a step system. You can order any edge profile in steps 3-steps flatter and 3-steps steeper.
The amount of edge lift change varies with the BOZR. Steeper radii will have a more significant change at 3-steps steeper than a flatter radius. The table opposite demonstrates the varying edge lift on different radii.
Considering this when changing edge profiles is useful, as the change may not be as significant as anticipated.
Edge Lift Chart
| BC = | 4.5mm | 6.5mm | 8.5mm |
| Step | EL (mm) | EL (mm) | EL (mm) |
| -3 | 1.58 | 0.29 | 0.14 |
| -2 | 0.58 | 0.29 | 0.14 |
| -1 | 1.6 | 0.31 | 0.15 |
| 0 | 1.65 | 0.36 | 0.2 |
| +1 | 1.72 | 0.39 | 0.21 |
| +2 | 1.74 | 0.4 | 0.22 |
| +3 | 1.75 | 0.41 | 0.22 |
Edge lift troubleshooting examples:
Pinch off
Start with a 1-step flat edge lift. This should be adequate in most cases. Then, flatten the edge lift until a 0.2 mm edge width is achieved.
Too much edge lift
Steepen the edge in 1-step increments until a 0.2mm edge width is achieved.
Inferior standoff
With a complex cornea such as a steep inferior cone, inferior standoff occurs. In these cases, you may choose the Quadrant-specific option. This allows for tucking in or steepening of the quadrant at 6 o’clock. The amount of lift reduction works the same way.
Fitting Set Parameters
| Number of lenses | 24 |
| Base curve | 4.60 – 6.90mm in 10mm increments |
| Total diameter | 8.70mm |
Parameters
| Materials |
Standard – Optimum Extra. Available in all materials |
| Diameter |
Standard – 8.80mm. Available 8.00mm to 9.90mm in 0.1mm increments |
| BVP |
4.50mm to 8.50mm in 0.05mm steps |
| Edge lift |
3 steps steeper and flatter |
| Power | -25.00D to +25.00D |
Dyna Z Cone Video Course
Check out our IC Specialist, Dyna Z Cone fitting course (registration required).
Contact Lens Wear Without Compromise
Using breakthrough manufacturing technology, Tangible Hydra-PEG bonds a 40nm hydrophilic coating to the surface of specialist contact lenses, significantly increasing wettability and lubricity.
The result? Happy patients who can enjoy a life of comfortable contact lens wear free from compromise.
Tangible Hydra-PEG is available with all No7 GP lenses. Just ask our Customer Care team to add Tangible Hydra-PEG when you place your next order.
Perfect for all GP patients, Tangible Hydra-PEG offers:
Increased wearing times
Improved ocular health
Superior surface properties
Improved wearing experience
“Brilliant! I’ve gone from using eye drops 5 times a day to 0...”
Keratoconus RGP wearer | 50+ years
Lens preference
Research shows that 70% of patients prefer a Tangible Hydra-PEG coated lens to their habitual, uncoated lens.
End of day comfort
67% of patients said they prefer a lens coated with Tangible Hydra-PEG than uncoated.
Dry eye comfort
When asked about comfort, dry eye patients rated lenses coated with Tangible Hydra-PEG ‘8 out of 10’, compared to ‘3 out of 10’ for uncoated.
%
70% prefer a Tangible Hydra-PEG coated lens
No7 Recommends - Ote Fine
All-in-one comfort solution for RGP contact lenses
Manufactured using the highest grade ingredients and exclusive to independent opticians, Oté Fine is the complete solution for all your RGP patients. Oté Fine is perfect for your EyeDream Ortho-k wearers too.
Kevin Taylor
Technical Director
We have a dedicated technical support team, headed by Kevin, with decades of experience ready to help and advise you on any fitting issues. If you need support, please call:
01424 850620
Frequently Asked Questions
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